Fraunhofer-Institut für Atmosphärische Umweltforschung IFU

Filters

77
77
76 1
Reset filters

Settings
Now showing 1 - 10 of 77
No Thumbnail Available
Publication

Determination of anthropogenic emission ratios in the Augsburg area from concentration ratios results from long-term measurements

2002 , Klemp, D. , Mannschreck, K. , Patz, H.W. , Habram, M. , Matuska, P. , Slemr, F.

View
No Thumbnail Available
Publication

Emissions of the city of Augsburg determined using the mass balance method

2002 , Kalthoff, N. , Corsmeier, U. , Schmidt, K. , Kottmeier, C. , Fiedler, F. , Habram, M. , Slemr, F.

Air quality models require emission data of air pollutants with high temporal and spatial resolution. The highly resolved emissions are calculated by complex emission models and may thus be subject to considerable uncertainties. To assess the uncertainty of the emission model calculations, emissions of the city of Augsburg in southern Germany were determined experimentally on several days in October 1998 using the technique of mass balance. Two algorithms were used to estimate the CO and NOx emissions from the data measured by two research aircraft, two tethered balloons, and an airship on the lateral surface enclosing the area of investigation. The two algorithms provided results which agree within the calculated uncertainties. The differences can be attributed mainly to the different interpolation methods applied to the layer between the lowest flight level and the ground. The measurements show that on the different weekdays both CO and NOx emissions varied by about a factor of two which is much larger than the variability predicted by the emission model. Higher than predicted CO emissions were observed on Saturday, 10 October 1998, whereas NOx emissions on 10 October were substantially smaller than predicted by the emission model.

View
No Thumbnail Available
Publication

Trace gas variations at Cape-Point, South-Africa, during may 1997 following a regional biomass burning episode

2001 , Brunke, E.G. , Labuschagne, C. , Scheel, H.E.

View
No Thumbnail Available
Publication

Physical features of the atmospheric aerosol determined with an aureolemeter and a FSSP probe in the mediterranean lampedusa island

2001 , Campanelli, M. , Junkermann, W. , Olivieri, B. , Tonna, G.

View
No Thumbnail Available
Publication

Statistical study of the diurnal variation of modeled and measured NMHC contributions

2002 , Möllmann-Coers, M. , Klemp, D. , Mannschreck, K. , Slemr, F.

The aim of the EVA project is to investigate the precision of modeled emission inventories for a city based on experimental data from two field campaigns in March and October 1998 (Slemr et al., J. Atmos. Chem., 2001). According to the results of the emission inventory model (Kühlwein et al., Atmos. Environ., this issue) for the campaigns, the measured nonmethane hydrocarbons (NMHCs) should originate predominantly from evaporation processes. In this paper these model results are discussed from a meteorological point of view. The results from atmospheric dispersion calculations with a Gaussian plume model are compared with measurements of NMHCs and CO at a site few kilometers downwind of the city of Augsburg. The dispersion model results point out that the correlations of the individual NMHCs against CO lead to different qualities of correlation for NMHCs co-emitted with CO (i.e. from combustion processes) and NMHCs which are not co-emitted with CO (i.e. from evaporation processes). However, using the correlation coefficients r2, as a measure of the quality of the correlation, the correlations of several NMHCs for which strong evaporation emissions are predicted from the emission inventory model do not show remarkable differences in the r2 when compared with the correlations for species predominantly emitted from combustion processes. Thus, the NMHC emissions are found to be dominated by emissions from combustion processes and the influence of evaporation processes on anthropogenic NMHC emissions seems to be considerably overestimated by the emission model. This is in agreement with the results of Mannschreck et al. (Atmos. Environ., 2001) which are based on the NMHC composition of the Augsburg city plume.

View
No Thumbnail Available
Publication

Determination of anthropogenic emissions in the Augsburg area by the source-tracer-ratio method

2002 , Möllmann-Coers, M. , Klemp, D. , Mannschreck, K. , Slemr, F.

Air-quality models require as input emission inventories of individual compounds high temporal and spatial resolution. These emission inventories are calculated by complex emission models. To evaluate these models, emission rates of CO and NOx of the city of Augsburg were determined in March and October using two independent methods and were compared with emission rates calculated by an emission model. This paper outlines the source-tracer-ratio (STR) method, describes its implementation in Augsburg, and presents the results obtained in four successful experiments. The CO emission rate was derived directly from the STR method, whereas the NOx emission rate is calculated from the CO emission rate using the average CO/NOx correlation in the city plume from the long-term dataset obtained within the Augsburg experiment. The CO and NOx emission rates obtained on 10, 22, and 23 October 1998, were in reasonable agreement with emission rates determined by a mass balance method. The CO emission rate on 23 March 1998, was about twice as large as the autumn emission rates. This observation is consistent with the observed mean emission ratios in March and October obtained from long-term measurements. The CO emission rates were also used to calculate absolute emission rates for a number of hydrocarbons.

View
No Thumbnail Available
Publication

A climatology of Be-7 at 4 high-altitude stations at the alps and the northern Apennines

2001 , Gerasopoulos, E. , Zanis, P. , Stohl, A. , Zerefos, C.S. , Papastefanou, C. , Ringer, W. , Tobler, L. , Hubener, S. , Gaggeler, H.W. , Kanter, H.J. , Tositti, L. , Sandrini, S.

View
No Thumbnail Available
Publication

Evaluation of an emission inventory by comparisons of modelled and measured emission ratios of individual HCs, CO and NOx

2002 , Mannschreck, K. , Klemp, D. , Kley, D. , Friedrich, R. , Kühlwein, J. , Wickert, B. , Matuska, P. , Habram, M. , Slemr, F.

Air quality models require emission inventories of individual compounds with high temporal and spatial resolution. These emission inventories are calculated by complex emission models. To evaluate these models, emission ratios of non-methane hydrocarbons (HCs, containing only H- and C-atoms), CO and NOx of the city of Augsburg were determined during two field campaigns in March and October 1998. The measured emission ratios have been compared with emission ratios calculated by an emission model at two accuracy levels. Only C-2-C-10 HCs were measured quantitatively by the applied techniques. C-11-C-13 HCs were measured with losses increasing with the number of C atoms, oxygenated and halogenated volatile organic compounds were not measured at all. The direct comparison could be made only for those HCs whose individual emissions can be specified by the model. They represent 21% of the total predicted volatile organic compound emissions and-according to the model-originate to a large percentage from traffic-related emission. The measured HCi/HCsum emission ratios (HCsum:=Sigma(HCi) for C-2-C-10-HCs and HCi:=mixing ratio of an individual hydrocarbon) for these compounds agreed within 30% for most compounds. The HCi/HCsum emission ratios measured in Augsburg are very similar to emission ratios from traffic-related sources suggesting that the emission model reflects the traffic emissions quite well. In order to consider all measured HCs for comparison the share of unspecified HCs, which are detectable by the GC system and should therefore be included in the experimental results, was estimated. Taking this into account yields a deviation between modelled and measured monthly mean values of HCi/CO and HCi/NOx of about 40%. The comparison of modelled and measured HCi/CO with HCi/HCsum emission ratios derived from the investigation based on single events confirms this finding: in this case an overestimation by the model of a factor of 1.5-2 was found. Since modelled and measured NOx and CO emissions agreed well within the uncertainty ranges, these deviations can be attributed to overestimation of HC emissions. Unspecified HC emissions mainly originate from solvent mixtures thus the overestimation of their emissions could explain the observed deviations. Regarding one specific HC which originates nearly exclusively from solvent emissions, i.e. n-decane, yields an overestimation of about a factor of 10 by the model.

View
No Thumbnail Available
Publication

Comparison of modelled and measured total CO and NOx emission rates

2002 , Kühlwein, J. , Friedrich, R. , Kalthoff, N. , Corsmeier, U. , Slemr, F. , Habram, M. , Möllmann-Coers, M.

Hourly total CO and NOx emission rates determined experimentally from the city of Augsburg, a medium-sized city in southern Germany, were compared with data calculated with a high-resolution emission model. Mass balances based on Aircraft measurements and tracer techniques were used to ascertain real-world emission conditions. On the other hand, comparative emission data were modelled at two different precision levels. A 'default level' represents a mesoscale emission model providing emissions highly resolved in time and space as input data for air quality models. Improved activity data obtained by measurements were used for emission calculations at a 'superior level'. Modelled and measured CO emission rates on working days, in general, were found to be in good agreement. CO emissions on Saturday were slightly underestimated by the model. Modelled NOx emission rates at both levels agree well with the measurements on working days. On Saturday, the modelled NOx emission rates are substantially higher than the measured ones, which represent only some 50-60% of the emission estimates. Comparisons between modelled hourly emissions from point sources and spatially highly resolved Aircraft measurements indicate that the temporal allocation of some industrial activities, especially of specific plants with irregular operating hours are very difficult to reflect by the model.

View
No Thumbnail Available
Publication

Assessing the meteorological conditions of a deep italian alpine valley system by means of a measuring campaign and simulations with 2 models during a summer smog episode

2001 , Dosio, A. , Emeis, S. , Graziani, G. , Junkermann, W. , Levy, A.

View